Here we present an observational study of the interaction of
the chromosphere with the TR moss, using a 2 hour time
sequence of high-cadence (30 s) TRACE C IV 1550 Å (0.1 MK),
Fe IX/X 171 Å (1 MK) and Fe XII 195 Å (1.5 MK) images, as
well as co-aligned, simultaneous SUMER spectra, and
ground-based filtergrams from the Swedish Vacuum Solar
Telescope (SVST, La Palma) in the wings of H-alpha. Detailed
comparisons of the H-alpha filtergrams (at -700, -350, +350
and +700 mÅ) with the TRACE C IV images reveals that there
is often a significant spatial correlation of the C IV
emission with the highly redshifted fibril or spicule-like
structures in H-alpha +700 mÅ. The discovery and detailed
quantitative study of this correlation promises to shed
light on the long outstanding issue of what role
chromospheric spicule-like jets play in the heating and
momentum balance of the outer atmosphere.

We have also quantitatively studied the auto-correlation and
cross-correlation time-scales of moss using a time sequence
of high cadence TRACE 171 Å and 195 Å images. In most of the
active region moss patch we studied, we find that the
emission of 1 and 1.5 MK plasma is highly correlated, but
often with significant negative and positive time delays.
Our results indicate that the footpoints of hot coronal
loops seem to undergo frequent cooling and heating on
time-scales of order fifteen minutes. By quantifying these
variations we can shed light on the temporal variability and
on the location of coronal heating in general.